shmem.c revision 2a7dba391e5628ad665ce84ef9a6648da541ebab
1/* 2 * Resizable virtual memory filesystem for Linux. 3 * 4 * Copyright (C) 2000 Linus Torvalds. 5 * 2000 Transmeta Corp. 6 * 2000-2001 Christoph Rohland 7 * 2000-2001 SAP AG 8 * 2002 Red Hat Inc. 9 * Copyright (C) 2002-2005 Hugh Dickins. 10 * Copyright (C) 2002-2005 VERITAS Software Corporation. 11 * Copyright (C) 2004 Andi Kleen, SuSE Labs 12 * 13 * Extended attribute support for tmpfs: 14 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net> 15 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com> 16 * 17 * tiny-shmem: 18 * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com> 19 * 20 * This file is released under the GPL. 21 */ 22 23#include <linux/fs.h> 24#include <linux/init.h> 25#include <linux/vfs.h> 26#include <linux/mount.h> 27#include <linux/pagemap.h> 28#include <linux/file.h> 29#include <linux/mm.h> 30#include <linux/module.h> 31#include <linux/percpu_counter.h> 32#include <linux/swap.h> 33 34static struct vfsmount *shm_mnt; 35 36#ifdef CONFIG_SHMEM 37/* 38 * This virtual memory filesystem is heavily based on the ramfs. It 39 * extends ramfs by the ability to use swap and honor resource limits 40 * which makes it a completely usable filesystem. 41 */ 42 43#include <linux/xattr.h> 44#include <linux/exportfs.h> 45#include <linux/posix_acl.h> 46#include <linux/generic_acl.h> 47#include <linux/mman.h> 48#include <linux/string.h> 49#include <linux/slab.h> 50#include <linux/backing-dev.h> 51#include <linux/shmem_fs.h> 52#include <linux/writeback.h> 53#include <linux/blkdev.h> 54#include <linux/security.h> 55#include <linux/swapops.h> 56#include <linux/mempolicy.h> 57#include <linux/namei.h> 58#include <linux/ctype.h> 59#include <linux/migrate.h> 60#include <linux/highmem.h> 61#include <linux/seq_file.h> 62#include <linux/magic.h> 63 64#include <asm/uaccess.h> 65#include <asm/div64.h> 66#include <asm/pgtable.h> 67 68/* 69 * The maximum size of a shmem/tmpfs file is limited by the maximum size of 70 * its triple-indirect swap vector - see illustration at shmem_swp_entry(). 71 * 72 * With 4kB page size, maximum file size is just over 2TB on a 32-bit kernel, 73 * but one eighth of that on a 64-bit kernel. With 8kB page size, maximum 74 * file size is just over 4TB on a 64-bit kernel, but 16TB on a 32-bit kernel, 75 * MAX_LFS_FILESIZE being then more restrictive than swap vector layout. 76 * 77 * We use / and * instead of shifts in the definitions below, so that the swap 78 * vector can be tested with small even values (e.g. 20) for ENTRIES_PER_PAGE. 79 */ 80#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long)) 81#define ENTRIES_PER_PAGEPAGE ((unsigned long long)ENTRIES_PER_PAGE*ENTRIES_PER_PAGE) 82 83#define SHMSWP_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1)) 84#define SHMSWP_MAX_BYTES (SHMSWP_MAX_INDEX << PAGE_CACHE_SHIFT) 85 86#define SHMEM_MAX_BYTES min_t(unsigned long long, SHMSWP_MAX_BYTES, MAX_LFS_FILESIZE) 87#define SHMEM_MAX_INDEX ((unsigned long)((SHMEM_MAX_BYTES+1) >> PAGE_CACHE_SHIFT)) 88 89#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) 90#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) 91 92/* info->flags needs VM_flags to handle pagein/truncate races efficiently */ 93#define SHMEM_PAGEIN VM_READ 94#define SHMEM_TRUNCATE VM_WRITE 95 96/* Definition to limit shmem_truncate's steps between cond_rescheds */ 97#define LATENCY_LIMIT 64 98 99/* Pretend that each entry is of this size in directory's i_size */ 100#define BOGO_DIRENT_SIZE 20 101 102/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */ 103enum sgp_type { 104 SGP_READ, /* don't exceed i_size, don't allocate page */ 105 SGP_CACHE, /* don't exceed i_size, may allocate page */ 106 SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */ 107 SGP_WRITE, /* may exceed i_size, may allocate page */ 108}; 109 110#ifdef CONFIG_TMPFS 111static unsigned long shmem_default_max_blocks(void) 112{ 113 return totalram_pages / 2; 114} 115 116static unsigned long shmem_default_max_inodes(void) 117{ 118 return min(totalram_pages - totalhigh_pages, totalram_pages / 2); 119} 120#endif 121 122static int shmem_getpage(struct inode *inode, unsigned long idx, 123 struct page **pagep, enum sgp_type sgp, int *type); 124 125static inline struct page *shmem_dir_alloc(gfp_t gfp_mask) 126{ 127 /* 128 * The above definition of ENTRIES_PER_PAGE, and the use of 129 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE: 130 * might be reconsidered if it ever diverges from PAGE_SIZE. 131 * 132 * Mobility flags are masked out as swap vectors cannot move 133 */ 134 return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO, 135 PAGE_CACHE_SHIFT-PAGE_SHIFT); 136} 137 138static inline void shmem_dir_free(struct page *page) 139{ 140 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT); 141} 142 143static struct page **shmem_dir_map(struct page *page) 144{ 145 return (struct page **)kmap_atomic(page, KM_USER0); 146} 147 148static inline void shmem_dir_unmap(struct page **dir) 149{ 150 kunmap_atomic(dir, KM_USER0); 151} 152 153static swp_entry_t *shmem_swp_map(struct page *page) 154{ 155 return (swp_entry_t *)kmap_atomic(page, KM_USER1); 156} 157 158static inline void shmem_swp_balance_unmap(void) 159{ 160 /* 161 * When passing a pointer to an i_direct entry, to code which 162 * also handles indirect entries and so will shmem_swp_unmap, 163 * we must arrange for the preempt count to remain in balance. 164 * What kmap_atomic of a lowmem page does depends on config 165 * and architecture, so pretend to kmap_atomic some lowmem page. 166 */ 167 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1); 168} 169 170static inline void shmem_swp_unmap(swp_entry_t *entry) 171{ 172 kunmap_atomic(entry, KM_USER1); 173} 174 175static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) 176{ 177 return sb->s_fs_info; 178} 179 180/* 181 * shmem_file_setup pre-accounts the whole fixed size of a VM object, 182 * for shared memory and for shared anonymous (/dev/zero) mappings 183 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), 184 * consistent with the pre-accounting of private mappings ... 185 */ 186static inline int shmem_acct_size(unsigned long flags, loff_t size) 187{ 188 return (flags & VM_NORESERVE) ? 189 0 : security_vm_enough_memory_kern(VM_ACCT(size)); 190} 191 192static inline void shmem_unacct_size(unsigned long flags, loff_t size) 193{ 194 if (!(flags & VM_NORESERVE)) 195 vm_unacct_memory(VM_ACCT(size)); 196} 197 198/* 199 * ... whereas tmpfs objects are accounted incrementally as 200 * pages are allocated, in order to allow huge sparse files. 201 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, 202 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. 203 */ 204static inline int shmem_acct_block(unsigned long flags) 205{ 206 return (flags & VM_NORESERVE) ? 207 security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE)) : 0; 208} 209 210static inline void shmem_unacct_blocks(unsigned long flags, long pages) 211{ 212 if (flags & VM_NORESERVE) 213 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); 214} 215 216static const struct super_operations shmem_ops; 217static const struct address_space_operations shmem_aops; 218static const struct file_operations shmem_file_operations; 219static const struct inode_operations shmem_inode_operations; 220static const struct inode_operations shmem_dir_inode_operations; 221static const struct inode_operations shmem_special_inode_operations; 222static const struct vm_operations_struct shmem_vm_ops; 223 224static struct backing_dev_info shmem_backing_dev_info __read_mostly = { 225 .ra_pages = 0, /* No readahead */ 226 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED, 227 .unplug_io_fn = default_unplug_io_fn, 228}; 229 230static LIST_HEAD(shmem_swaplist); 231static DEFINE_MUTEX(shmem_swaplist_mutex); 232 233static void shmem_free_blocks(struct inode *inode, long pages) 234{ 235 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 236 if (sbinfo->max_blocks) { 237 percpu_counter_add(&sbinfo->used_blocks, -pages); 238 spin_lock(&inode->i_lock); 239 inode->i_blocks -= pages*BLOCKS_PER_PAGE; 240 spin_unlock(&inode->i_lock); 241 } 242} 243 244static int shmem_reserve_inode(struct super_block *sb) 245{ 246 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 247 if (sbinfo->max_inodes) { 248 spin_lock(&sbinfo->stat_lock); 249 if (!sbinfo->free_inodes) { 250 spin_unlock(&sbinfo->stat_lock); 251 return -ENOSPC; 252 } 253 sbinfo->free_inodes--; 254 spin_unlock(&sbinfo->stat_lock); 255 } 256 return 0; 257} 258 259static void shmem_free_inode(struct super_block *sb) 260{ 261 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 262 if (sbinfo->max_inodes) { 263 spin_lock(&sbinfo->stat_lock); 264 sbinfo->free_inodes++; 265 spin_unlock(&sbinfo->stat_lock); 266 } 267} 268 269/** 270 * shmem_recalc_inode - recalculate the size of an inode 271 * @inode: inode to recalc 272 * 273 * We have to calculate the free blocks since the mm can drop 274 * undirtied hole pages behind our back. 275 * 276 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped 277 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) 278 * 279 * It has to be called with the spinlock held. 280 */ 281static void shmem_recalc_inode(struct inode *inode) 282{ 283 struct shmem_inode_info *info = SHMEM_I(inode); 284 long freed; 285 286 freed = info->alloced - info->swapped - inode->i_mapping->nrpages; 287 if (freed > 0) { 288 info->alloced -= freed; 289 shmem_unacct_blocks(info->flags, freed); 290 shmem_free_blocks(inode, freed); 291 } 292} 293 294/** 295 * shmem_swp_entry - find the swap vector position in the info structure 296 * @info: info structure for the inode 297 * @index: index of the page to find 298 * @page: optional page to add to the structure. Has to be preset to 299 * all zeros 300 * 301 * If there is no space allocated yet it will return NULL when 302 * page is NULL, else it will use the page for the needed block, 303 * setting it to NULL on return to indicate that it has been used. 304 * 305 * The swap vector is organized the following way: 306 * 307 * There are SHMEM_NR_DIRECT entries directly stored in the 308 * shmem_inode_info structure. So small files do not need an addional 309 * allocation. 310 * 311 * For pages with index > SHMEM_NR_DIRECT there is the pointer 312 * i_indirect which points to a page which holds in the first half 313 * doubly indirect blocks, in the second half triple indirect blocks: 314 * 315 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the 316 * following layout (for SHMEM_NR_DIRECT == 16): 317 * 318 * i_indirect -> dir --> 16-19 319 * | +-> 20-23 320 * | 321 * +-->dir2 --> 24-27 322 * | +-> 28-31 323 * | +-> 32-35 324 * | +-> 36-39 325 * | 326 * +-->dir3 --> 40-43 327 * +-> 44-47 328 * +-> 48-51 329 * +-> 52-55 330 */ 331static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page) 332{ 333 unsigned long offset; 334 struct page **dir; 335 struct page *subdir; 336 337 if (index < SHMEM_NR_DIRECT) { 338 shmem_swp_balance_unmap(); 339 return info->i_direct+index; 340 } 341 if (!info->i_indirect) { 342 if (page) { 343 info->i_indirect = *page; 344 *page = NULL; 345 } 346 return NULL; /* need another page */ 347 } 348 349 index -= SHMEM_NR_DIRECT; 350 offset = index % ENTRIES_PER_PAGE; 351 index /= ENTRIES_PER_PAGE; 352 dir = shmem_dir_map(info->i_indirect); 353 354 if (index >= ENTRIES_PER_PAGE/2) { 355 index -= ENTRIES_PER_PAGE/2; 356 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE; 357 index %= ENTRIES_PER_PAGE; 358 subdir = *dir; 359 if (!subdir) { 360 if (page) { 361 *dir = *page; 362 *page = NULL; 363 } 364 shmem_dir_unmap(dir); 365 return NULL; /* need another page */ 366 } 367 shmem_dir_unmap(dir); 368 dir = shmem_dir_map(subdir); 369 } 370 371 dir += index; 372 subdir = *dir; 373 if (!subdir) { 374 if (!page || !(subdir = *page)) { 375 shmem_dir_unmap(dir); 376 return NULL; /* need a page */ 377 } 378 *dir = subdir; 379 *page = NULL; 380 } 381 shmem_dir_unmap(dir); 382 return shmem_swp_map(subdir) + offset; 383} 384 385static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value) 386{ 387 long incdec = value? 1: -1; 388 389 entry->val = value; 390 info->swapped += incdec; 391 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) { 392 struct page *page = kmap_atomic_to_page(entry); 393 set_page_private(page, page_private(page) + incdec); 394 } 395} 396 397/** 398 * shmem_swp_alloc - get the position of the swap entry for the page. 399 * @info: info structure for the inode 400 * @index: index of the page to find 401 * @sgp: check and recheck i_size? skip allocation? 402 * 403 * If the entry does not exist, allocate it. 404 */ 405static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp) 406{ 407 struct inode *inode = &info->vfs_inode; 408 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 409 struct page *page = NULL; 410 swp_entry_t *entry; 411 412 if (sgp != SGP_WRITE && 413 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 414 return ERR_PTR(-EINVAL); 415 416 while (!(entry = shmem_swp_entry(info, index, &page))) { 417 if (sgp == SGP_READ) 418 return shmem_swp_map(ZERO_PAGE(0)); 419 /* 420 * Test used_blocks against 1 less max_blocks, since we have 1 data 421 * page (and perhaps indirect index pages) yet to allocate: 422 * a waste to allocate index if we cannot allocate data. 423 */ 424 if (sbinfo->max_blocks) { 425 if (percpu_counter_compare(&sbinfo->used_blocks, (sbinfo->max_blocks - 1)) > 0) 426 return ERR_PTR(-ENOSPC); 427 percpu_counter_inc(&sbinfo->used_blocks); 428 spin_lock(&inode->i_lock); 429 inode->i_blocks += BLOCKS_PER_PAGE; 430 spin_unlock(&inode->i_lock); 431 } 432 433 spin_unlock(&info->lock); 434 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping)); 435 spin_lock(&info->lock); 436 437 if (!page) { 438 shmem_free_blocks(inode, 1); 439 return ERR_PTR(-ENOMEM); 440 } 441 if (sgp != SGP_WRITE && 442 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { 443 entry = ERR_PTR(-EINVAL); 444 break; 445 } 446 if (info->next_index <= index) 447 info->next_index = index + 1; 448 } 449 if (page) { 450 /* another task gave its page, or truncated the file */ 451 shmem_free_blocks(inode, 1); 452 shmem_dir_free(page); 453 } 454 if (info->next_index <= index && !IS_ERR(entry)) 455 info->next_index = index + 1; 456 return entry; 457} 458 459/** 460 * shmem_free_swp - free some swap entries in a directory 461 * @dir: pointer to the directory 462 * @edir: pointer after last entry of the directory 463 * @punch_lock: pointer to spinlock when needed for the holepunch case 464 */ 465static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir, 466 spinlock_t *punch_lock) 467{ 468 spinlock_t *punch_unlock = NULL; 469 swp_entry_t *ptr; 470 int freed = 0; 471 472 for (ptr = dir; ptr < edir; ptr++) { 473 if (ptr->val) { 474 if (unlikely(punch_lock)) { 475 punch_unlock = punch_lock; 476 punch_lock = NULL; 477 spin_lock(punch_unlock); 478 if (!ptr->val) 479 continue; 480 } 481 free_swap_and_cache(*ptr); 482 *ptr = (swp_entry_t){0}; 483 freed++; 484 } 485 } 486 if (punch_unlock) 487 spin_unlock(punch_unlock); 488 return freed; 489} 490 491static int shmem_map_and_free_swp(struct page *subdir, int offset, 492 int limit, struct page ***dir, spinlock_t *punch_lock) 493{ 494 swp_entry_t *ptr; 495 int freed = 0; 496 497 ptr = shmem_swp_map(subdir); 498 for (; offset < limit; offset += LATENCY_LIMIT) { 499 int size = limit - offset; 500 if (size > LATENCY_LIMIT) 501 size = LATENCY_LIMIT; 502 freed += shmem_free_swp(ptr+offset, ptr+offset+size, 503 punch_lock); 504 if (need_resched()) { 505 shmem_swp_unmap(ptr); 506 if (*dir) { 507 shmem_dir_unmap(*dir); 508 *dir = NULL; 509 } 510 cond_resched(); 511 ptr = shmem_swp_map(subdir); 512 } 513 } 514 shmem_swp_unmap(ptr); 515 return freed; 516} 517 518static void shmem_free_pages(struct list_head *next) 519{ 520 struct page *page; 521 int freed = 0; 522 523 do { 524 page = container_of(next, struct page, lru); 525 next = next->next; 526 shmem_dir_free(page); 527 freed++; 528 if (freed >= LATENCY_LIMIT) { 529 cond_resched(); 530 freed = 0; 531 } 532 } while (next); 533} 534 535static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end) 536{ 537 struct shmem_inode_info *info = SHMEM_I(inode); 538 unsigned long idx; 539 unsigned long size; 540 unsigned long limit; 541 unsigned long stage; 542 unsigned long diroff; 543 struct page **dir; 544 struct page *topdir; 545 struct page *middir; 546 struct page *subdir; 547 swp_entry_t *ptr; 548 LIST_HEAD(pages_to_free); 549 long nr_pages_to_free = 0; 550 long nr_swaps_freed = 0; 551 int offset; 552 int freed; 553 int punch_hole; 554 spinlock_t *needs_lock; 555 spinlock_t *punch_lock; 556 unsigned long upper_limit; 557 558 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 559 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 560 if (idx >= info->next_index) 561 return; 562 563 spin_lock(&info->lock); 564 info->flags |= SHMEM_TRUNCATE; 565 if (likely(end == (loff_t) -1)) { 566 limit = info->next_index; 567 upper_limit = SHMEM_MAX_INDEX; 568 info->next_index = idx; 569 needs_lock = NULL; 570 punch_hole = 0; 571 } else { 572 if (end + 1 >= inode->i_size) { /* we may free a little more */ 573 limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >> 574 PAGE_CACHE_SHIFT; 575 upper_limit = SHMEM_MAX_INDEX; 576 } else { 577 limit = (end + 1) >> PAGE_CACHE_SHIFT; 578 upper_limit = limit; 579 } 580 needs_lock = &info->lock; 581 punch_hole = 1; 582 } 583 584 topdir = info->i_indirect; 585 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) { 586 info->i_indirect = NULL; 587 nr_pages_to_free++; 588 list_add(&topdir->lru, &pages_to_free); 589 } 590 spin_unlock(&info->lock); 591 592 if (info->swapped && idx < SHMEM_NR_DIRECT) { 593 ptr = info->i_direct; 594 size = limit; 595 if (size > SHMEM_NR_DIRECT) 596 size = SHMEM_NR_DIRECT; 597 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock); 598 } 599 600 /* 601 * If there are no indirect blocks or we are punching a hole 602 * below indirect blocks, nothing to be done. 603 */ 604 if (!topdir || limit <= SHMEM_NR_DIRECT) 605 goto done2; 606 607 /* 608 * The truncation case has already dropped info->lock, and we're safe 609 * because i_size and next_index have already been lowered, preventing 610 * access beyond. But in the punch_hole case, we still need to take 611 * the lock when updating the swap directory, because there might be 612 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or 613 * shmem_writepage. However, whenever we find we can remove a whole 614 * directory page (not at the misaligned start or end of the range), 615 * we first NULLify its pointer in the level above, and then have no 616 * need to take the lock when updating its contents: needs_lock and 617 * punch_lock (either pointing to info->lock or NULL) manage this. 618 */ 619 620 upper_limit -= SHMEM_NR_DIRECT; 621 limit -= SHMEM_NR_DIRECT; 622 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0; 623 offset = idx % ENTRIES_PER_PAGE; 624 idx -= offset; 625 626 dir = shmem_dir_map(topdir); 627 stage = ENTRIES_PER_PAGEPAGE/2; 628 if (idx < ENTRIES_PER_PAGEPAGE/2) { 629 middir = topdir; 630 diroff = idx/ENTRIES_PER_PAGE; 631 } else { 632 dir += ENTRIES_PER_PAGE/2; 633 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE; 634 while (stage <= idx) 635 stage += ENTRIES_PER_PAGEPAGE; 636 middir = *dir; 637 if (*dir) { 638 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) % 639 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE; 640 if (!diroff && !offset && upper_limit >= stage) { 641 if (needs_lock) { 642 spin_lock(needs_lock); 643 *dir = NULL; 644 spin_unlock(needs_lock); 645 needs_lock = NULL; 646 } else 647 *dir = NULL; 648 nr_pages_to_free++; 649 list_add(&middir->lru, &pages_to_free); 650 } 651 shmem_dir_unmap(dir); 652 dir = shmem_dir_map(middir); 653 } else { 654 diroff = 0; 655 offset = 0; 656 idx = stage; 657 } 658 } 659 660 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) { 661 if (unlikely(idx == stage)) { 662 shmem_dir_unmap(dir); 663 dir = shmem_dir_map(topdir) + 664 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 665 while (!*dir) { 666 dir++; 667 idx += ENTRIES_PER_PAGEPAGE; 668 if (idx >= limit) 669 goto done1; 670 } 671 stage = idx + ENTRIES_PER_PAGEPAGE; 672 middir = *dir; 673 if (punch_hole) 674 needs_lock = &info->lock; 675 if (upper_limit >= stage) { 676 if (needs_lock) { 677 spin_lock(needs_lock); 678 *dir = NULL; 679 spin_unlock(needs_lock); 680 needs_lock = NULL; 681 } else 682 *dir = NULL; 683 nr_pages_to_free++; 684 list_add(&middir->lru, &pages_to_free); 685 } 686 shmem_dir_unmap(dir); 687 cond_resched(); 688 dir = shmem_dir_map(middir); 689 diroff = 0; 690 } 691 punch_lock = needs_lock; 692 subdir = dir[diroff]; 693 if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) { 694 if (needs_lock) { 695 spin_lock(needs_lock); 696 dir[diroff] = NULL; 697 spin_unlock(needs_lock); 698 punch_lock = NULL; 699 } else 700 dir[diroff] = NULL; 701 nr_pages_to_free++; 702 list_add(&subdir->lru, &pages_to_free); 703 } 704 if (subdir && page_private(subdir) /* has swap entries */) { 705 size = limit - idx; 706 if (size > ENTRIES_PER_PAGE) 707 size = ENTRIES_PER_PAGE; 708 freed = shmem_map_and_free_swp(subdir, 709 offset, size, &dir, punch_lock); 710 if (!dir) 711 dir = shmem_dir_map(middir); 712 nr_swaps_freed += freed; 713 if (offset || punch_lock) { 714 spin_lock(&info->lock); 715 set_page_private(subdir, 716 page_private(subdir) - freed); 717 spin_unlock(&info->lock); 718 } else 719 BUG_ON(page_private(subdir) != freed); 720 } 721 offset = 0; 722 } 723done1: 724 shmem_dir_unmap(dir); 725done2: 726 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) { 727 /* 728 * Call truncate_inode_pages again: racing shmem_unuse_inode 729 * may have swizzled a page in from swap since 730 * truncate_pagecache or generic_delete_inode did it, before we 731 * lowered next_index. Also, though shmem_getpage checks 732 * i_size before adding to cache, no recheck after: so fix the 733 * narrow window there too. 734 * 735 * Recalling truncate_inode_pages_range and unmap_mapping_range 736 * every time for punch_hole (which never got a chance to clear 737 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive, 738 * yet hardly ever necessary: try to optimize them out later. 739 */ 740 truncate_inode_pages_range(inode->i_mapping, start, end); 741 if (punch_hole) 742 unmap_mapping_range(inode->i_mapping, start, 743 end - start, 1); 744 } 745 746 spin_lock(&info->lock); 747 info->flags &= ~SHMEM_TRUNCATE; 748 info->swapped -= nr_swaps_freed; 749 if (nr_pages_to_free) 750 shmem_free_blocks(inode, nr_pages_to_free); 751 shmem_recalc_inode(inode); 752 spin_unlock(&info->lock); 753 754 /* 755 * Empty swap vector directory pages to be freed? 756 */ 757 if (!list_empty(&pages_to_free)) { 758 pages_to_free.prev->next = NULL; 759 shmem_free_pages(pages_to_free.next); 760 } 761} 762 763static int shmem_notify_change(struct dentry *dentry, struct iattr *attr) 764{ 765 struct inode *inode = dentry->d_inode; 766 loff_t newsize = attr->ia_size; 767 int error; 768 769 error = inode_change_ok(inode, attr); 770 if (error) 771 return error; 772 773 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE) 774 && newsize != inode->i_size) { 775 struct page *page = NULL; 776 777 if (newsize < inode->i_size) { 778 /* 779 * If truncating down to a partial page, then 780 * if that page is already allocated, hold it 781 * in memory until the truncation is over, so 782 * truncate_partial_page cannnot miss it were 783 * it assigned to swap. 784 */ 785 if (newsize & (PAGE_CACHE_SIZE-1)) { 786 (void) shmem_getpage(inode, 787 newsize >> PAGE_CACHE_SHIFT, 788 &page, SGP_READ, NULL); 789 if (page) 790 unlock_page(page); 791 } 792 /* 793 * Reset SHMEM_PAGEIN flag so that shmem_truncate can 794 * detect if any pages might have been added to cache 795 * after truncate_inode_pages. But we needn't bother 796 * if it's being fully truncated to zero-length: the 797 * nrpages check is efficient enough in that case. 798 */ 799 if (newsize) { 800 struct shmem_inode_info *info = SHMEM_I(inode); 801 spin_lock(&info->lock); 802 info->flags &= ~SHMEM_PAGEIN; 803 spin_unlock(&info->lock); 804 } 805 } 806 807 /* XXX(truncate): truncate_setsize should be called last */ 808 truncate_setsize(inode, newsize); 809 if (page) 810 page_cache_release(page); 811 shmem_truncate_range(inode, newsize, (loff_t)-1); 812 } 813 814 setattr_copy(inode, attr); 815#ifdef CONFIG_TMPFS_POSIX_ACL 816 if (attr->ia_valid & ATTR_MODE) 817 error = generic_acl_chmod(inode); 818#endif 819 return error; 820} 821 822static void shmem_evict_inode(struct inode *inode) 823{ 824 struct shmem_inode_info *info = SHMEM_I(inode); 825 826 if (inode->i_mapping->a_ops == &shmem_aops) { 827 truncate_inode_pages(inode->i_mapping, 0); 828 shmem_unacct_size(info->flags, inode->i_size); 829 inode->i_size = 0; 830 shmem_truncate_range(inode, 0, (loff_t)-1); 831 if (!list_empty(&info->swaplist)) { 832 mutex_lock(&shmem_swaplist_mutex); 833 list_del_init(&info->swaplist); 834 mutex_unlock(&shmem_swaplist_mutex); 835 } 836 } 837 BUG_ON(inode->i_blocks); 838 shmem_free_inode(inode->i_sb); 839 end_writeback(inode); 840} 841 842static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir) 843{ 844 swp_entry_t *ptr; 845 846 for (ptr = dir; ptr < edir; ptr++) { 847 if (ptr->val == entry.val) 848 return ptr - dir; 849 } 850 return -1; 851} 852 853static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) 854{ 855 struct inode *inode; 856 unsigned long idx; 857 unsigned long size; 858 unsigned long limit; 859 unsigned long stage; 860 struct page **dir; 861 struct page *subdir; 862 swp_entry_t *ptr; 863 int offset; 864 int error; 865 866 idx = 0; 867 ptr = info->i_direct; 868 spin_lock(&info->lock); 869 if (!info->swapped) { 870 list_del_init(&info->swaplist); 871 goto lost2; 872 } 873 limit = info->next_index; 874 size = limit; 875 if (size > SHMEM_NR_DIRECT) 876 size = SHMEM_NR_DIRECT; 877 offset = shmem_find_swp(entry, ptr, ptr+size); 878 if (offset >= 0) 879 goto found; 880 if (!info->i_indirect) 881 goto lost2; 882 883 dir = shmem_dir_map(info->i_indirect); 884 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2; 885 886 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) { 887 if (unlikely(idx == stage)) { 888 shmem_dir_unmap(dir-1); 889 if (cond_resched_lock(&info->lock)) { 890 /* check it has not been truncated */ 891 if (limit > info->next_index) { 892 limit = info->next_index; 893 if (idx >= limit) 894 goto lost2; 895 } 896 } 897 dir = shmem_dir_map(info->i_indirect) + 898 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 899 while (!*dir) { 900 dir++; 901 idx += ENTRIES_PER_PAGEPAGE; 902 if (idx >= limit) 903 goto lost1; 904 } 905 stage = idx + ENTRIES_PER_PAGEPAGE; 906 subdir = *dir; 907 shmem_dir_unmap(dir); 908 dir = shmem_dir_map(subdir); 909 } 910 subdir = *dir; 911 if (subdir && page_private(subdir)) { 912 ptr = shmem_swp_map(subdir); 913 size = limit - idx; 914 if (size > ENTRIES_PER_PAGE) 915 size = ENTRIES_PER_PAGE; 916 offset = shmem_find_swp(entry, ptr, ptr+size); 917 shmem_swp_unmap(ptr); 918 if (offset >= 0) { 919 shmem_dir_unmap(dir); 920 goto found; 921 } 922 } 923 } 924lost1: 925 shmem_dir_unmap(dir-1); 926lost2: 927 spin_unlock(&info->lock); 928 return 0; 929found: 930 idx += offset; 931 inode = igrab(&info->vfs_inode); 932 spin_unlock(&info->lock); 933 934 /* 935 * Move _head_ to start search for next from here. 936 * But be careful: shmem_evict_inode checks list_empty without taking 937 * mutex, and there's an instant in list_move_tail when info->swaplist 938 * would appear empty, if it were the only one on shmem_swaplist. We 939 * could avoid doing it if inode NULL; or use this minor optimization. 940 */ 941 if (shmem_swaplist.next != &info->swaplist) 942 list_move_tail(&shmem_swaplist, &info->swaplist); 943 mutex_unlock(&shmem_swaplist_mutex); 944 945 error = 1; 946 if (!inode) 947 goto out; 948 /* 949 * Charge page using GFP_KERNEL while we can wait. 950 * Charged back to the user(not to caller) when swap account is used. 951 * add_to_page_cache() will be called with GFP_NOWAIT. 952 */ 953 error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL); 954 if (error) 955 goto out; 956 error = radix_tree_preload(GFP_KERNEL); 957 if (error) { 958 mem_cgroup_uncharge_cache_page(page); 959 goto out; 960 } 961 error = 1; 962 963 spin_lock(&info->lock); 964 ptr = shmem_swp_entry(info, idx, NULL); 965 if (ptr && ptr->val == entry.val) { 966 error = add_to_page_cache_locked(page, inode->i_mapping, 967 idx, GFP_NOWAIT); 968 /* does mem_cgroup_uncharge_cache_page on error */ 969 } else /* we must compensate for our precharge above */ 970 mem_cgroup_uncharge_cache_page(page); 971 972 if (error == -EEXIST) { 973 struct page *filepage = find_get_page(inode->i_mapping, idx); 974 error = 1; 975 if (filepage) { 976 /* 977 * There might be a more uptodate page coming down 978 * from a stacked writepage: forget our swappage if so. 979 */ 980 if (PageUptodate(filepage)) 981 error = 0; 982 page_cache_release(filepage); 983 } 984 } 985 if (!error) { 986 delete_from_swap_cache(page); 987 set_page_dirty(page); 988 info->flags |= SHMEM_PAGEIN; 989 shmem_swp_set(info, ptr, 0); 990 swap_free(entry); 991 error = 1; /* not an error, but entry was found */ 992 } 993 if (ptr) 994 shmem_swp_unmap(ptr); 995 spin_unlock(&info->lock); 996 radix_tree_preload_end(); 997out: 998 unlock_page(page); 999 page_cache_release(page); 1000 iput(inode); /* allows for NULL */ 1001 return error; 1002} 1003 1004/* 1005 * shmem_unuse() search for an eventually swapped out shmem page. 1006 */ 1007int shmem_unuse(swp_entry_t entry, struct page *page) 1008{ 1009 struct list_head *p, *next; 1010 struct shmem_inode_info *info; 1011 int found = 0; 1012 1013 mutex_lock(&shmem_swaplist_mutex); 1014 list_for_each_safe(p, next, &shmem_swaplist) { 1015 info = list_entry(p, struct shmem_inode_info, swaplist); 1016 found = shmem_unuse_inode(info, entry, page); 1017 cond_resched(); 1018 if (found) 1019 goto out; 1020 } 1021 mutex_unlock(&shmem_swaplist_mutex); 1022 /* 1023 * Can some race bring us here? We've been holding page lock, 1024 * so I think not; but would rather try again later than BUG() 1025 */ 1026 unlock_page(page); 1027 page_cache_release(page); 1028out: 1029 return (found < 0) ? found : 0; 1030} 1031 1032/* 1033 * Move the page from the page cache to the swap cache. 1034 */ 1035static int shmem_writepage(struct page *page, struct writeback_control *wbc) 1036{ 1037 struct shmem_inode_info *info; 1038 swp_entry_t *entry, swap; 1039 struct address_space *mapping; 1040 unsigned long index; 1041 struct inode *inode; 1042 1043 BUG_ON(!PageLocked(page)); 1044 mapping = page->mapping; 1045 index = page->index; 1046 inode = mapping->host; 1047 info = SHMEM_I(inode); 1048 if (info->flags & VM_LOCKED) 1049 goto redirty; 1050 if (!total_swap_pages) 1051 goto redirty; 1052 1053 /* 1054 * shmem_backing_dev_info's capabilities prevent regular writeback or 1055 * sync from ever calling shmem_writepage; but a stacking filesystem 1056 * may use the ->writepage of its underlying filesystem, in which case 1057 * tmpfs should write out to swap only in response to memory pressure, 1058 * and not for the writeback threads or sync. However, in those cases, 1059 * we do still want to check if there's a redundant swappage to be 1060 * discarded. 1061 */ 1062 if (wbc->for_reclaim) 1063 swap = get_swap_page(); 1064 else 1065 swap.val = 0; 1066 1067 spin_lock(&info->lock); 1068 if (index >= info->next_index) { 1069 BUG_ON(!(info->flags & SHMEM_TRUNCATE)); 1070 goto unlock; 1071 } 1072 entry = shmem_swp_entry(info, index, NULL); 1073 if (entry->val) { 1074 /* 1075 * The more uptodate page coming down from a stacked 1076 * writepage should replace our old swappage. 1077 */ 1078 free_swap_and_cache(*entry); 1079 shmem_swp_set(info, entry, 0); 1080 } 1081 shmem_recalc_inode(inode); 1082 1083 if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { 1084 remove_from_page_cache(page); 1085 shmem_swp_set(info, entry, swap.val); 1086 shmem_swp_unmap(entry); 1087 if (list_empty(&info->swaplist)) 1088 inode = igrab(inode); 1089 else 1090 inode = NULL; 1091 spin_unlock(&info->lock); 1092 swap_shmem_alloc(swap); 1093 BUG_ON(page_mapped(page)); 1094 page_cache_release(page); /* pagecache ref */ 1095 swap_writepage(page, wbc); 1096 if (inode) { 1097 mutex_lock(&shmem_swaplist_mutex); 1098 /* move instead of add in case we're racing */ 1099 list_move_tail(&info->swaplist, &shmem_swaplist); 1100 mutex_unlock(&shmem_swaplist_mutex); 1101 iput(inode); 1102 } 1103 return 0; 1104 } 1105 1106 shmem_swp_unmap(entry); 1107unlock: 1108 spin_unlock(&info->lock); 1109 /* 1110 * add_to_swap_cache() doesn't return -EEXIST, so we can safely 1111 * clear SWAP_HAS_CACHE flag. 1112 */ 1113 swapcache_free(swap, NULL); 1114redirty: 1115 set_page_dirty(page); 1116 if (wbc->for_reclaim) 1117 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ 1118 unlock_page(page); 1119 return 0; 1120} 1121 1122#ifdef CONFIG_NUMA 1123#ifdef CONFIG_TMPFS 1124static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) 1125{ 1126 char buffer[64]; 1127 1128 if (!mpol || mpol->mode == MPOL_DEFAULT) 1129 return; /* show nothing */ 1130 1131 mpol_to_str(buffer, sizeof(buffer), mpol, 1); 1132 1133 seq_printf(seq, ",mpol=%s", buffer); 1134} 1135 1136static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) 1137{ 1138 struct mempolicy *mpol = NULL; 1139 if (sbinfo->mpol) { 1140 spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */ 1141 mpol = sbinfo->mpol; 1142 mpol_get(mpol); 1143 spin_unlock(&sbinfo->stat_lock); 1144 } 1145 return mpol; 1146} 1147#endif /* CONFIG_TMPFS */ 1148 1149static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, 1150 struct shmem_inode_info *info, unsigned long idx) 1151{ 1152 struct mempolicy mpol, *spol; 1153 struct vm_area_struct pvma; 1154 struct page *page; 1155 1156 spol = mpol_cond_copy(&mpol, 1157 mpol_shared_policy_lookup(&info->policy, idx)); 1158 1159 /* Create a pseudo vma that just contains the policy */ 1160 pvma.vm_start = 0; 1161 pvma.vm_pgoff = idx; 1162 pvma.vm_ops = NULL; 1163 pvma.vm_policy = spol; 1164 page = swapin_readahead(entry, gfp, &pvma, 0); 1165 return page; 1166} 1167 1168static struct page *shmem_alloc_page(gfp_t gfp, 1169 struct shmem_inode_info *info, unsigned long idx) 1170{ 1171 struct vm_area_struct pvma; 1172 1173 /* Create a pseudo vma that just contains the policy */ 1174 pvma.vm_start = 0; 1175 pvma.vm_pgoff = idx; 1176 pvma.vm_ops = NULL; 1177 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 1178 1179 /* 1180 * alloc_page_vma() will drop the shared policy reference 1181 */ 1182 return alloc_page_vma(gfp, &pvma, 0); 1183} 1184#else /* !CONFIG_NUMA */ 1185#ifdef CONFIG_TMPFS 1186static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *p) 1187{ 1188} 1189#endif /* CONFIG_TMPFS */ 1190 1191static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, 1192 struct shmem_inode_info *info, unsigned long idx) 1193{ 1194 return swapin_readahead(entry, gfp, NULL, 0); 1195} 1196 1197static inline struct page *shmem_alloc_page(gfp_t gfp, 1198 struct shmem_inode_info *info, unsigned long idx) 1199{ 1200 return alloc_page(gfp); 1201} 1202#endif /* CONFIG_NUMA */ 1203 1204#if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS) 1205static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) 1206{ 1207 return NULL; 1208} 1209#endif 1210 1211/* 1212 * shmem_getpage - either get the page from swap or allocate a new one 1213 * 1214 * If we allocate a new one we do not mark it dirty. That's up to the 1215 * vm. If we swap it in we mark it dirty since we also free the swap 1216 * entry since a page cannot live in both the swap and page cache 1217 */ 1218static int shmem_getpage(struct inode *inode, unsigned long idx, 1219 struct page **pagep, enum sgp_type sgp, int *type) 1220{ 1221 struct address_space *mapping = inode->i_mapping; 1222 struct shmem_inode_info *info = SHMEM_I(inode); 1223 struct shmem_sb_info *sbinfo; 1224 struct page *filepage = *pagep; 1225 struct page *swappage; 1226 struct page *prealloc_page = NULL; 1227 swp_entry_t *entry; 1228 swp_entry_t swap; 1229 gfp_t gfp; 1230 int error; 1231 1232 if (idx >= SHMEM_MAX_INDEX) 1233 return -EFBIG; 1234 1235 if (type) 1236 *type = 0; 1237 1238 /* 1239 * Normally, filepage is NULL on entry, and either found 1240 * uptodate immediately, or allocated and zeroed, or read 1241 * in under swappage, which is then assigned to filepage. 1242 * But shmem_readpage (required for splice) passes in a locked 1243 * filepage, which may be found not uptodate by other callers 1244 * too, and may need to be copied from the swappage read in. 1245 */ 1246repeat: 1247 if (!filepage) 1248 filepage = find_lock_page(mapping, idx); 1249 if (filepage && PageUptodate(filepage)) 1250 goto done; 1251 gfp = mapping_gfp_mask(mapping); 1252 if (!filepage) { 1253 /* 1254 * Try to preload while we can wait, to not make a habit of 1255 * draining atomic reserves; but don't latch on to this cpu. 1256 */ 1257 error = radix_tree_preload(gfp & ~__GFP_HIGHMEM); 1258 if (error) 1259 goto failed; 1260 radix_tree_preload_end(); 1261 if (sgp != SGP_READ && !prealloc_page) { 1262 /* We don't care if this fails */ 1263 prealloc_page = shmem_alloc_page(gfp, info, idx); 1264 if (prealloc_page) { 1265 if (mem_cgroup_cache_charge(prealloc_page, 1266 current->mm, GFP_KERNEL)) { 1267 page_cache_release(prealloc_page); 1268 prealloc_page = NULL; 1269 } 1270 } 1271 } 1272 } 1273 error = 0; 1274 1275 spin_lock(&info->lock); 1276 shmem_recalc_inode(inode); 1277 entry = shmem_swp_alloc(info, idx, sgp); 1278 if (IS_ERR(entry)) { 1279 spin_unlock(&info->lock); 1280 error = PTR_ERR(entry); 1281 goto failed; 1282 } 1283 swap = *entry; 1284 1285 if (swap.val) { 1286 /* Look it up and read it in.. */ 1287 swappage = lookup_swap_cache(swap); 1288 if (!swappage) { 1289 shmem_swp_unmap(entry); 1290 /* here we actually do the io */ 1291 if (type && !(*type & VM_FAULT_MAJOR)) { 1292 __count_vm_event(PGMAJFAULT); 1293 *type |= VM_FAULT_MAJOR; 1294 } 1295 spin_unlock(&info->lock); 1296 swappage = shmem_swapin(swap, gfp, info, idx); 1297 if (!swappage) { 1298 spin_lock(&info->lock); 1299 entry = shmem_swp_alloc(info, idx, sgp); 1300 if (IS_ERR(entry)) 1301 error = PTR_ERR(entry); 1302 else { 1303 if (entry->val == swap.val) 1304 error = -ENOMEM; 1305 shmem_swp_unmap(entry); 1306 } 1307 spin_unlock(&info->lock); 1308 if (error) 1309 goto failed; 1310 goto repeat; 1311 } 1312 wait_on_page_locked(swappage); 1313 page_cache_release(swappage); 1314 goto repeat; 1315 } 1316 1317 /* We have to do this with page locked to prevent races */ 1318 if (!trylock_page(swappage)) { 1319 shmem_swp_unmap(entry); 1320 spin_unlock(&info->lock); 1321 wait_on_page_locked(swappage); 1322 page_cache_release(swappage); 1323 goto repeat; 1324 } 1325 if (PageWriteback(swappage)) { 1326 shmem_swp_unmap(entry); 1327 spin_unlock(&info->lock); 1328 wait_on_page_writeback(swappage); 1329 unlock_page(swappage); 1330 page_cache_release(swappage); 1331 goto repeat; 1332 } 1333 if (!PageUptodate(swappage)) { 1334 shmem_swp_unmap(entry); 1335 spin_unlock(&info->lock); 1336 unlock_page(swappage); 1337 page_cache_release(swappage); 1338 error = -EIO; 1339 goto failed; 1340 } 1341 1342 if (filepage) { 1343 shmem_swp_set(info, entry, 0); 1344 shmem_swp_unmap(entry); 1345 delete_from_swap_cache(swappage); 1346 spin_unlock(&info->lock); 1347 copy_highpage(filepage, swappage); 1348 unlock_page(swappage); 1349 page_cache_release(swappage); 1350 flush_dcache_page(filepage); 1351 SetPageUptodate(filepage); 1352 set_page_dirty(filepage); 1353 swap_free(swap); 1354 } else if (!(error = add_to_page_cache_locked(swappage, mapping, 1355 idx, GFP_NOWAIT))) { 1356 info->flags |= SHMEM_PAGEIN; 1357 shmem_swp_set(info, entry, 0); 1358 shmem_swp_unmap(entry); 1359 delete_from_swap_cache(swappage); 1360 spin_unlock(&info->lock); 1361 filepage = swappage; 1362 set_page_dirty(filepage); 1363 swap_free(swap); 1364 } else { 1365 shmem_swp_unmap(entry); 1366 spin_unlock(&info->lock); 1367 if (error == -ENOMEM) { 1368 /* 1369 * reclaim from proper memory cgroup and 1370 * call memcg's OOM if needed. 1371 */ 1372 error = mem_cgroup_shmem_charge_fallback( 1373 swappage, 1374 current->mm, 1375 gfp); 1376 if (error) { 1377 unlock_page(swappage); 1378 page_cache_release(swappage); 1379 goto failed; 1380 } 1381 } 1382 unlock_page(swappage); 1383 page_cache_release(swappage); 1384 goto repeat; 1385 } 1386 } else if (sgp == SGP_READ && !filepage) { 1387 shmem_swp_unmap(entry); 1388 filepage = find_get_page(mapping, idx); 1389 if (filepage && 1390 (!PageUptodate(filepage) || !trylock_page(filepage))) { 1391 spin_unlock(&info->lock); 1392 wait_on_page_locked(filepage); 1393 page_cache_release(filepage); 1394 filepage = NULL; 1395 goto repeat; 1396 } 1397 spin_unlock(&info->lock); 1398 } else { 1399 shmem_swp_unmap(entry); 1400 sbinfo = SHMEM_SB(inode->i_sb); 1401 if (sbinfo->max_blocks) { 1402 if ((percpu_counter_compare(&sbinfo->used_blocks, sbinfo->max_blocks) > 0) || 1403 shmem_acct_block(info->flags)) { 1404 spin_unlock(&info->lock); 1405 error = -ENOSPC; 1406 goto failed; 1407 } 1408 percpu_counter_inc(&sbinfo->used_blocks); 1409 spin_lock(&inode->i_lock); 1410 inode->i_blocks += BLOCKS_PER_PAGE; 1411 spin_unlock(&inode->i_lock); 1412 } else if (shmem_acct_block(info->flags)) { 1413 spin_unlock(&info->lock); 1414 error = -ENOSPC; 1415 goto failed; 1416 } 1417 1418 if (!filepage) { 1419 int ret; 1420 1421 if (!prealloc_page) { 1422 spin_unlock(&info->lock); 1423 filepage = shmem_alloc_page(gfp, info, idx); 1424 if (!filepage) { 1425 shmem_unacct_blocks(info->flags, 1); 1426 shmem_free_blocks(inode, 1); 1427 error = -ENOMEM; 1428 goto failed; 1429 } 1430 SetPageSwapBacked(filepage); 1431 1432 /* 1433 * Precharge page while we can wait, compensate 1434 * after 1435 */ 1436 error = mem_cgroup_cache_charge(filepage, 1437 current->mm, GFP_KERNEL); 1438 if (error) { 1439 page_cache_release(filepage); 1440 shmem_unacct_blocks(info->flags, 1); 1441 shmem_free_blocks(inode, 1); 1442 filepage = NULL; 1443 goto failed; 1444 } 1445 1446 spin_lock(&info->lock); 1447 } else { 1448 filepage = prealloc_page; 1449 prealloc_page = NULL; 1450 SetPageSwapBacked(filepage); 1451 } 1452 1453 entry = shmem_swp_alloc(info, idx, sgp); 1454 if (IS_ERR(entry)) 1455 error = PTR_ERR(entry); 1456 else { 1457 swap = *entry; 1458 shmem_swp_unmap(entry); 1459 } 1460 ret = error || swap.val; 1461 if (ret) 1462 mem_cgroup_uncharge_cache_page(filepage); 1463 else 1464 ret = add_to_page_cache_lru(filepage, mapping, 1465 idx, GFP_NOWAIT); 1466 /* 1467 * At add_to_page_cache_lru() failure, uncharge will 1468 * be done automatically. 1469 */ 1470 if (ret) { 1471 spin_unlock(&info->lock); 1472 page_cache_release(filepage); 1473 shmem_unacct_blocks(info->flags, 1); 1474 shmem_free_blocks(inode, 1); 1475 filepage = NULL; 1476 if (error) 1477 goto failed; 1478 goto repeat; 1479 } 1480 info->flags |= SHMEM_PAGEIN; 1481 } 1482 1483 info->alloced++; 1484 spin_unlock(&info->lock); 1485 clear_highpage(filepage); 1486 flush_dcache_page(filepage); 1487 SetPageUptodate(filepage); 1488 if (sgp == SGP_DIRTY) 1489 set_page_dirty(filepage); 1490 } 1491done: 1492 *pagep = filepage; 1493 error = 0; 1494 goto out; 1495 1496failed: 1497 if (*pagep != filepage) { 1498 unlock_page(filepage); 1499 page_cache_release(filepage); 1500 } 1501out: 1502 if (prealloc_page) { 1503 mem_cgroup_uncharge_cache_page(prealloc_page); 1504 page_cache_release(prealloc_page); 1505 } 1506 return error; 1507} 1508 1509static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 1510{ 1511 struct inode *inode = vma->vm_file->f_path.dentry->d_inode; 1512 int error; 1513 int ret; 1514 1515 if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 1516 return VM_FAULT_SIGBUS; 1517 1518 error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); 1519 if (error) 1520 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); 1521 1522 return ret | VM_FAULT_LOCKED; 1523} 1524 1525#ifdef CONFIG_NUMA 1526static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) 1527{ 1528 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1529 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); 1530} 1531 1532static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, 1533 unsigned long addr) 1534{ 1535 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1536 unsigned long idx; 1537 1538 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 1539 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); 1540} 1541#endif 1542 1543int shmem_lock(struct file *file, int lock, struct user_struct *user) 1544{ 1545 struct inode *inode = file->f_path.dentry->d_inode; 1546 struct shmem_inode_info *info = SHMEM_I(inode); 1547 int retval = -ENOMEM; 1548 1549 spin_lock(&info->lock); 1550 if (lock && !(info->flags & VM_LOCKED)) { 1551 if (!user_shm_lock(inode->i_size, user)) 1552 goto out_nomem; 1553 info->flags |= VM_LOCKED; 1554 mapping_set_unevictable(file->f_mapping); 1555 } 1556 if (!lock && (info->flags & VM_LOCKED) && user) { 1557 user_shm_unlock(inode->i_size, user); 1558 info->flags &= ~VM_LOCKED; 1559 mapping_clear_unevictable(file->f_mapping); 1560 scan_mapping_unevictable_pages(file->f_mapping); 1561 } 1562 retval = 0; 1563 1564out_nomem: 1565 spin_unlock(&info->lock); 1566 return retval; 1567} 1568 1569static int shmem_mmap(struct file *file, struct vm_area_struct *vma) 1570{ 1571 file_accessed(file); 1572 vma->vm_ops = &shmem_vm_ops; 1573 vma->vm_flags |= VM_CAN_NONLINEAR; 1574 return 0; 1575} 1576 1577static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir, 1578 int mode, dev_t dev, unsigned long flags) 1579{ 1580 struct inode *inode; 1581 struct shmem_inode_info *info; 1582 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1583 1584 if (shmem_reserve_inode(sb)) 1585 return NULL; 1586 1587 inode = new_inode(sb); 1588 if (inode) { 1589 inode->i_ino = get_next_ino(); 1590 inode_init_owner(inode, dir, mode); 1591 inode->i_blocks = 0; 1592 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; 1593 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 1594 inode->i_generation = get_seconds(); 1595 info = SHMEM_I(inode); 1596 memset(info, 0, (char *)inode - (char *)info); 1597 spin_lock_init(&info->lock); 1598 info->flags = flags & VM_NORESERVE; 1599 INIT_LIST_HEAD(&info->swaplist); 1600 cache_no_acl(inode); 1601 1602 switch (mode & S_IFMT) { 1603 default: 1604 inode->i_op = &shmem_special_inode_operations; 1605 init_special_inode(inode, mode, dev); 1606 break; 1607 case S_IFREG: 1608 inode->i_mapping->a_ops = &shmem_aops; 1609 inode->i_op = &shmem_inode_operations; 1610 inode->i_fop = &shmem_file_operations; 1611 mpol_shared_policy_init(&info->policy, 1612 shmem_get_sbmpol(sbinfo)); 1613 break; 1614 case S_IFDIR: 1615 inc_nlink(inode); 1616 /* Some things misbehave if size == 0 on a directory */ 1617 inode->i_size = 2 * BOGO_DIRENT_SIZE; 1618 inode->i_op = &shmem_dir_inode_operations; 1619 inode->i_fop = &simple_dir_operations; 1620 break; 1621 case S_IFLNK: 1622 /* 1623 * Must not load anything in the rbtree, 1624 * mpol_free_shared_policy will not be called. 1625 */ 1626 mpol_shared_policy_init(&info->policy, NULL); 1627 break; 1628 } 1629 } else 1630 shmem_free_inode(sb); 1631 return inode; 1632} 1633 1634#ifdef CONFIG_TMPFS 1635static const struct inode_operations shmem_symlink_inode_operations; 1636static const struct inode_operations shmem_symlink_inline_operations; 1637 1638/* 1639 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin; 1640 * but providing them allows a tmpfs file to be used for splice, sendfile, and 1641 * below the loop driver, in the generic fashion that many filesystems support. 1642 */ 1643static int shmem_readpage(struct file *file, struct page *page) 1644{ 1645 struct inode *inode = page->mapping->host; 1646 int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL); 1647 unlock_page(page); 1648 return error; 1649} 1650 1651static int 1652shmem_write_begin(struct file *file, struct address_space *mapping, 1653 loff_t pos, unsigned len, unsigned flags, 1654 struct page **pagep, void **fsdata) 1655{ 1656 struct inode *inode = mapping->host; 1657 pgoff_t index = pos >> PAGE_CACHE_SHIFT; 1658 *pagep = NULL; 1659 return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); 1660} 1661 1662static int 1663shmem_write_end(struct file *file, struct address_space *mapping, 1664 loff_t pos, unsigned len, unsigned copied, 1665 struct page *page, void *fsdata) 1666{ 1667 struct inode *inode = mapping->host; 1668 1669 if (pos + copied > inode->i_size) 1670 i_size_write(inode, pos + copied); 1671 1672 set_page_dirty(page); 1673 unlock_page(page); 1674 page_cache_release(page); 1675 1676 return copied; 1677} 1678 1679static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) 1680{ 1681 struct inode *inode = filp->f_path.dentry->d_inode; 1682 struct address_space *mapping = inode->i_mapping; 1683 unsigned long index, offset; 1684 enum sgp_type sgp = SGP_READ; 1685 1686 /* 1687 * Might this read be for a stacking filesystem? Then when reading 1688 * holes of a sparse file, we actually need to allocate those pages, 1689 * and even mark them dirty, so it cannot exceed the max_blocks limit. 1690 */ 1691 if (segment_eq(get_fs(), KERNEL_DS)) 1692 sgp = SGP_DIRTY; 1693 1694 index = *ppos >> PAGE_CACHE_SHIFT; 1695 offset = *ppos & ~PAGE_CACHE_MASK; 1696 1697 for (;;) { 1698 struct page *page = NULL; 1699 unsigned long end_index, nr, ret; 1700 loff_t i_size = i_size_read(inode); 1701 1702 end_index = i_size >> PAGE_CACHE_SHIFT; 1703 if (index > end_index) 1704 break; 1705 if (index == end_index) { 1706 nr = i_size & ~PAGE_CACHE_MASK; 1707 if (nr <= offset) 1708 break; 1709 } 1710 1711 desc->error = shmem_getpage(inode, index, &page, sgp, NULL); 1712 if (desc->error) { 1713 if (desc->error == -EINVAL) 1714 desc->error = 0; 1715 break; 1716 } 1717 if (page) 1718 unlock_page(page); 1719 1720 /* 1721 * We must evaluate after, since reads (unlike writes) 1722 * are called without i_mutex protection against truncate 1723 */ 1724 nr = PAGE_CACHE_SIZE; 1725 i_size = i_size_read(inode); 1726 end_index = i_size >> PAGE_CACHE_SHIFT; 1727 if (index == end_index) { 1728 nr = i_size & ~PAGE_CACHE_MASK; 1729 if (nr <= offset) { 1730 if (page) 1731 page_cache_release(page); 1732 break; 1733 } 1734 } 1735 nr -= offset; 1736 1737 if (page) { 1738 /* 1739 * If users can be writing to this page using arbitrary 1740 * virtual addresses, take care about potential aliasing 1741 * before reading the page on the kernel side. 1742 */ 1743 if (mapping_writably_mapped(mapping)) 1744 flush_dcache_page(page); 1745 /* 1746 * Mark the page accessed if we read the beginning. 1747 */ 1748 if (!offset) 1749 mark_page_accessed(page); 1750 } else { 1751 page = ZERO_PAGE(0); 1752 page_cache_get(page); 1753 } 1754 1755 /* 1756 * Ok, we have the page, and it's up-to-date, so 1757 * now we can copy it to user space... 1758 * 1759 * The actor routine returns how many bytes were actually used.. 1760 * NOTE! This may not be the same as how much of a user buffer 1761 * we filled up (we may be padding etc), so we can only update 1762 * "pos" here (the actor routine has to update the user buffer 1763 * pointers and the remaining count). 1764 */ 1765 ret = actor(desc, page, offset, nr); 1766 offset += ret; 1767 index += offset >> PAGE_CACHE_SHIFT; 1768 offset &= ~PAGE_CACHE_MASK; 1769 1770 page_cache_release(page); 1771 if (ret != nr || !desc->count) 1772 break; 1773 1774 cond_resched(); 1775 } 1776 1777 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 1778 file_accessed(filp); 1779} 1780 1781static ssize_t shmem_file_aio_read(struct kiocb *iocb, 1782 const struct iovec *iov, unsigned long nr_segs, loff_t pos) 1783{ 1784 struct file *filp = iocb->ki_filp; 1785 ssize_t retval; 1786 unsigned long seg; 1787 size_t count; 1788 loff_t *ppos = &iocb->ki_pos; 1789 1790 retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); 1791 if (retval) 1792 return retval; 1793 1794 for (seg = 0; seg < nr_segs; seg++) { 1795 read_descriptor_t desc; 1796 1797 desc.written = 0; 1798 desc.arg.buf = iov[seg].iov_base; 1799 desc.count = iov[seg].iov_len; 1800 if (desc.count == 0) 1801 continue; 1802 desc.error = 0; 1803 do_shmem_file_read(filp, ppos, &desc, file_read_actor); 1804 retval += desc.written; 1805 if (desc.error) { 1806 retval = retval ?: desc.error; 1807 break; 1808 } 1809 if (desc.count > 0) 1810 break; 1811 } 1812 return retval; 1813} 1814 1815static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) 1816{ 1817 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); 1818 1819 buf->f_type = TMPFS_MAGIC; 1820 buf->f_bsize = PAGE_CACHE_SIZE; 1821 buf->f_namelen = NAME_MAX; 1822 if (sbinfo->max_blocks) { 1823 buf->f_blocks = sbinfo->max_blocks; 1824 buf->f_bavail = buf->f_bfree = 1825 sbinfo->max_blocks - percpu_counter_sum(&sbinfo->used_blocks); 1826 } 1827 if (sbinfo->max_inodes) { 1828 buf->f_files = sbinfo->max_inodes; 1829 buf->f_ffree = sbinfo->free_inodes; 1830 } 1831 /* else leave those fields 0 like simple_statfs */ 1832 return 0; 1833} 1834 1835/* 1836 * File creation. Allocate an inode, and we're done.. 1837 */ 1838static int 1839shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 1840{ 1841 struct inode *inode; 1842 int error = -ENOSPC; 1843 1844 inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE); 1845 if (inode) { 1846 error = security_inode_init_security(inode, dir, 1847 &dentry->d_name, NULL, 1848 NULL, NULL); 1849 if (error) { 1850 if (error != -EOPNOTSUPP) { 1851 iput(inode); 1852 return error; 1853 } 1854 } 1855#ifdef CONFIG_TMPFS_POSIX_ACL 1856 error = generic_acl_init(inode, dir); 1857 if (error) { 1858 iput(inode); 1859 return error; 1860 } 1861#else 1862 error = 0; 1863#endif 1864 dir->i_size += BOGO_DIRENT_SIZE; 1865 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1866 d_instantiate(dentry, inode); 1867 dget(dentry); /* Extra count - pin the dentry in core */ 1868 } 1869 return error; 1870} 1871 1872static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) 1873{ 1874 int error; 1875 1876 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) 1877 return error; 1878 inc_nlink(dir); 1879 return 0; 1880} 1881 1882static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, 1883 struct nameidata *nd) 1884{ 1885 return shmem_mknod(dir, dentry, mode | S_IFREG, 0); 1886} 1887 1888/* 1889 * Link a file.. 1890 */ 1891static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 1892{ 1893 struct inode *inode = old_dentry->d_inode; 1894 int ret; 1895 1896 /* 1897 * No ordinary (disk based) filesystem counts links as inodes; 1898 * but each new link needs a new dentry, pinning lowmem, and 1899 * tmpfs dentries cannot be pruned until they are unlinked. 1900 */ 1901 ret = shmem_reserve_inode(inode->i_sb); 1902 if (ret) 1903 goto out; 1904 1905 dir->i_size += BOGO_DIRENT_SIZE; 1906 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1907 inc_nlink(inode); 1908 ihold(inode); /* New dentry reference */ 1909 dget(dentry); /* Extra pinning count for the created dentry */ 1910 d_instantiate(dentry, inode); 1911out: 1912 return ret; 1913} 1914 1915static int shmem_unlink(struct inode *dir, struct dentry *dentry) 1916{ 1917 struct inode *inode = dentry->d_inode; 1918 1919 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) 1920 shmem_free_inode(inode->i_sb); 1921 1922 dir->i_size -= BOGO_DIRENT_SIZE; 1923 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1924 drop_nlink(inode); 1925 dput(dentry); /* Undo the count from "create" - this does all the work */ 1926 return 0; 1927} 1928 1929static int shmem_rmdir(struct inode *dir, struct dentry *dentry) 1930{ 1931 if (!simple_empty(dentry)) 1932 return -ENOTEMPTY; 1933 1934 drop_nlink(dentry->d_inode); 1935 drop_nlink(dir); 1936 return shmem_unlink(dir, dentry); 1937} 1938 1939/* 1940 * The VFS layer already does all the dentry stuff for rename, 1941 * we just have to decrement the usage count for the target if 1942 * it exists so that the VFS layer correctly free's it when it 1943 * gets overwritten. 1944 */ 1945static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) 1946{ 1947 struct inode *inode = old_dentry->d_inode; 1948 int they_are_dirs = S_ISDIR(inode->i_mode); 1949 1950 if (!simple_empty(new_dentry)) 1951 return -ENOTEMPTY; 1952 1953 if (new_dentry->d_inode) { 1954 (void) shmem_unlink(new_dir, new_dentry); 1955 if (they_are_dirs) 1956 drop_nlink(old_dir); 1957 } else if (they_are_dirs) { 1958 drop_nlink(old_dir); 1959 inc_nlink(new_dir); 1960 } 1961 1962 old_dir->i_size -= BOGO_DIRENT_SIZE; 1963 new_dir->i_size += BOGO_DIRENT_SIZE; 1964 old_dir->i_ctime = old_dir->i_mtime = 1965 new_dir->i_ctime = new_dir->i_mtime = 1966 inode->i_ctime = CURRENT_TIME; 1967 return 0; 1968} 1969 1970static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) 1971{ 1972 int error; 1973 int len; 1974 struct inode *inode; 1975 struct page *page = NULL; 1976 char *kaddr; 1977 struct shmem_inode_info *info; 1978 1979 len = strlen(symname) + 1; 1980 if (len > PAGE_CACHE_SIZE) 1981 return -ENAMETOOLONG; 1982 1983 inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE); 1984 if (!inode) 1985 return -ENOSPC; 1986 1987 error = security_inode_init_security(inode, dir, &dentry->d_name, NULL, 1988 NULL, NULL); 1989 if (error) { 1990 if (error != -EOPNOTSUPP) { 1991 iput(inode); 1992 return error; 1993 } 1994 error = 0; 1995 } 1996 1997 info = SHMEM_I(inode); 1998 inode->i_size = len-1; 1999 if (len <= (char *)inode - (char *)info) { 2000 /* do it inline */ 2001 memcpy(info, symname, len); 2002 inode->i_op = &shmem_symlink_inline_operations; 2003 } else { 2004 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); 2005 if (error) { 2006 iput(inode); 2007 return error; 2008 } 2009 inode->i_mapping->a_ops = &shmem_aops; 2010 inode->i_op = &shmem_symlink_inode_operations; 2011 kaddr = kmap_atomic(page, KM_USER0); 2012 memcpy(kaddr, symname, len); 2013 kunmap_atomic(kaddr, KM_USER0); 2014 set_page_dirty(page); 2015 unlock_page(page); 2016 page_cache_release(page); 2017 } 2018 dir->i_size += BOGO_DIRENT_SIZE; 2019 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 2020 d_instantiate(dentry, inode); 2021 dget(dentry); 2022 return 0; 2023} 2024 2025static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) 2026{ 2027 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); 2028 return NULL; 2029} 2030 2031static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) 2032{ 2033 struct page *page = NULL; 2034 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); 2035 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); 2036 if (page) 2037 unlock_page(page); 2038 return page; 2039} 2040 2041static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 2042{ 2043 if (!IS_ERR(nd_get_link(nd))) { 2044 struct page *page = cookie; 2045 kunmap(page); 2046 mark_page_accessed(page); 2047 page_cache_release(page); 2048 } 2049} 2050 2051static const struct inode_operations shmem_symlink_inline_operations = { 2052 .readlink = generic_readlink, 2053 .follow_link = shmem_follow_link_inline, 2054}; 2055 2056static const struct inode_operations shmem_symlink_inode_operations = { 2057 .readlink = generic_readlink, 2058 .follow_link = shmem_follow_link, 2059 .put_link = shmem_put_link, 2060}; 2061 2062#ifdef CONFIG_TMPFS_POSIX_ACL 2063/* 2064 * Superblocks without xattr inode operations will get security.* xattr 2065 * support from the VFS "for free". As soon as we have any other xattrs 2066 * like ACLs, we also need to implement the security.* handlers at 2067 * filesystem level, though. 2068 */ 2069 2070static size_t shmem_xattr_security_list(struct dentry *dentry, char *list, 2071 size_t list_len, const char *name, 2072 size_t name_len, int handler_flags) 2073{ 2074 return security_inode_listsecurity(dentry->d_inode, list, list_len); 2075} 2076 2077static int shmem_xattr_security_get(struct dentry *dentry, const char *name, 2078 void *buffer, size_t size, int handler_flags) 2079{ 2080 if (strcmp(name, "") == 0) 2081 return -EINVAL; 2082 return xattr_getsecurity(dentry->d_inode, name, buffer, size); 2083} 2084 2085static int shmem_xattr_security_set(struct dentry *dentry, const char *name, 2086 const void *value, size_t size, int flags, int handler_flags) 2087{ 2088 if (strcmp(name, "") == 0) 2089 return -EINVAL; 2090 return security_inode_setsecurity(dentry->d_inode, name, value, 2091 size, flags); 2092} 2093 2094static const struct xattr_handler shmem_xattr_security_handler = { 2095 .prefix = XATTR_SECURITY_PREFIX, 2096 .list = shmem_xattr_security_list, 2097 .get = shmem_xattr_security_get, 2098 .set = shmem_xattr_security_set, 2099}; 2100 2101static const struct xattr_handler *shmem_xattr_handlers[] = { 2102 &generic_acl_access_handler, 2103 &generic_acl_default_handler, 2104 &shmem_xattr_security_handler, 2105 NULL 2106}; 2107#endif 2108 2109static struct dentry *shmem_get_parent(struct dentry *child) 2110{ 2111 return ERR_PTR(-ESTALE); 2112} 2113 2114static int shmem_match(struct inode *ino, void *vfh) 2115{ 2116 __u32 *fh = vfh; 2117 __u64 inum = fh[2]; 2118 inum = (inum << 32) | fh[1]; 2119 return ino->i_ino == inum && fh[0] == ino->i_generation; 2120} 2121 2122static struct dentry *shmem_fh_to_dentry(struct super_block *sb, 2123 struct fid *fid, int fh_len, int fh_type) 2124{ 2125 struct inode *inode; 2126 struct dentry *dentry = NULL; 2127 u64 inum = fid->raw[2]; 2128 inum = (inum << 32) | fid->raw[1]; 2129 2130 if (fh_len < 3) 2131 return NULL; 2132 2133 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), 2134 shmem_match, fid->raw); 2135 if (inode) { 2136 dentry = d_find_alias(inode); 2137 iput(inode); 2138 } 2139 2140 return dentry; 2141} 2142 2143static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len, 2144 int connectable) 2145{ 2146 struct inode *inode = dentry->d_inode; 2147 2148 if (*len < 3) 2149 return 255; 2150 2151 if (inode_unhashed(inode)) { 2152 /* Unfortunately insert_inode_hash is not idempotent, 2153 * so as we hash inodes here rather than at creation 2154 * time, we need a lock to ensure we only try 2155 * to do it once 2156 */ 2157 static DEFINE_SPINLOCK(lock); 2158 spin_lock(&lock); 2159 if (inode_unhashed(inode)) 2160 __insert_inode_hash(inode, 2161 inode->i_ino + inode->i_generation); 2162 spin_unlock(&lock); 2163 } 2164 2165 fh[0] = inode->i_generation; 2166 fh[1] = inode->i_ino; 2167 fh[2] = ((__u64)inode->i_ino) >> 32; 2168 2169 *len = 3; 2170 return 1; 2171} 2172 2173static const struct export_operations shmem_export_ops = { 2174 .get_parent = shmem_get_parent, 2175 .encode_fh = shmem_encode_fh, 2176 .fh_to_dentry = shmem_fh_to_dentry, 2177}; 2178 2179static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo, 2180 bool remount) 2181{ 2182 char *this_char, *value, *rest; 2183 2184 while (options != NULL) { 2185 this_char = options; 2186 for (;;) { 2187 /* 2188 * NUL-terminate this option: unfortunately, 2189 * mount options form a comma-separated list, 2190 * but mpol's nodelist may also contain commas. 2191 */ 2192 options = strchr(options, ','); 2193 if (options == NULL) 2194 break; 2195 options++; 2196 if (!isdigit(*options)) { 2197 options[-1] = '\0'; 2198 break; 2199 } 2200 } 2201 if (!*this_char) 2202 continue; 2203 if ((value = strchr(this_char,'=')) != NULL) { 2204 *value++ = 0; 2205 } else { 2206 printk(KERN_ERR 2207 "tmpfs: No value for mount option '%s'\n", 2208 this_char); 2209 return 1; 2210 } 2211 2212 if (!strcmp(this_char,"size")) { 2213 unsigned long long size; 2214 size = memparse(value,&rest); 2215 if (*rest == '%') { 2216 size <<= PAGE_SHIFT; 2217 size *= totalram_pages; 2218 do_div(size, 100); 2219 rest++; 2220 } 2221 if (*rest) 2222 goto bad_val; 2223 sbinfo->max_blocks = 2224 DIV_ROUND_UP(size, PAGE_CACHE_SIZE); 2225 } else if (!strcmp(this_char,"nr_blocks")) { 2226 sbinfo->max_blocks = memparse(value, &rest); 2227 if (*rest) 2228 goto bad_val; 2229 } else if (!strcmp(this_char,"nr_inodes")) { 2230 sbinfo->max_inodes = memparse(value, &rest); 2231 if (*rest) 2232 goto bad_val; 2233 } else if (!strcmp(this_char,"mode")) { 2234 if (remount) 2235 continue; 2236 sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777; 2237 if (*rest) 2238 goto bad_val; 2239 } else if (!strcmp(this_char,"uid")) { 2240 if (remount) 2241 continue; 2242 sbinfo->uid = simple_strtoul(value, &rest, 0); 2243 if (*rest) 2244 goto bad_val; 2245 } else if (!strcmp(this_char,"gid")) { 2246 if (remount) 2247 continue; 2248 sbinfo->gid = simple_strtoul(value, &rest, 0); 2249 if (*rest) 2250 goto bad_val; 2251 } else if (!strcmp(this_char,"mpol")) { 2252 if (mpol_parse_str(value, &sbinfo->mpol, 1)) 2253 goto bad_val; 2254 } else { 2255 printk(KERN_ERR "tmpfs: Bad mount option %s\n", 2256 this_char); 2257 return 1; 2258 } 2259 } 2260 return 0; 2261 2262bad_val: 2263 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", 2264 value, this_char); 2265 return 1; 2266 2267} 2268 2269static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) 2270{ 2271 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 2272 struct shmem_sb_info config = *sbinfo; 2273 unsigned long inodes; 2274 int error = -EINVAL; 2275 2276 if (shmem_parse_options(data, &config, true)) 2277 return error; 2278 2279 spin_lock(&sbinfo->stat_lock); 2280 inodes = sbinfo->max_inodes - sbinfo->free_inodes; 2281 if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0) 2282 goto out; 2283 if (config.max_inodes < inodes) 2284 goto out; 2285 /* 2286 * Those tests also disallow limited->unlimited while any are in 2287 * use, so i_blocks will always be zero when max_blocks is zero; 2288 * but we must separately disallow unlimited->limited, because 2289 * in that case we have no record of how much is already in use. 2290 */ 2291 if (config.max_blocks && !sbinfo->max_blocks) 2292 goto out; 2293 if (config.max_inodes && !sbinfo->max_inodes) 2294 goto out; 2295 2296 error = 0; 2297 sbinfo->max_blocks = config.max_blocks; 2298 sbinfo->max_inodes = config.max_inodes; 2299 sbinfo->free_inodes = config.max_inodes - inodes; 2300 2301 mpol_put(sbinfo->mpol); 2302 sbinfo->mpol = config.mpol; /* transfers initial ref */ 2303out: 2304 spin_unlock(&sbinfo->stat_lock); 2305 return error; 2306} 2307 2308static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs) 2309{ 2310 struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb); 2311 2312 if (sbinfo->max_blocks != shmem_default_max_blocks()) 2313 seq_printf(seq, ",size=%luk", 2314 sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10)); 2315 if (sbinfo->max_inodes != shmem_default_max_inodes()) 2316 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes); 2317 if (sbinfo->mode != (S_IRWXUGO | S_ISVTX)) 2318 seq_printf(seq, ",mode=%03o", sbinfo->mode); 2319 if (sbinfo->uid != 0) 2320 seq_printf(seq, ",uid=%u", sbinfo->uid); 2321 if (sbinfo->gid != 0) 2322 seq_printf(seq, ",gid=%u", sbinfo->gid); 2323 shmem_show_mpol(seq, sbinfo->mpol); 2324 return 0; 2325} 2326#endif /* CONFIG_TMPFS */ 2327 2328static void shmem_put_super(struct super_block *sb) 2329{ 2330 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 2331 2332 percpu_counter_destroy(&sbinfo->used_blocks); 2333 kfree(sbinfo); 2334 sb->s_fs_info = NULL; 2335} 2336 2337int shmem_fill_super(struct super_block *sb, void *data, int silent) 2338{ 2339 struct inode *inode; 2340 struct dentry *root; 2341 struct shmem_sb_info *sbinfo; 2342 int err = -ENOMEM; 2343 2344 /* Round up to L1_CACHE_BYTES to resist false sharing */ 2345 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info), 2346 L1_CACHE_BYTES), GFP_KERNEL); 2347 if (!sbinfo) 2348 return -ENOMEM; 2349 2350 sbinfo->mode = S_IRWXUGO | S_ISVTX; 2351 sbinfo->uid = current_fsuid(); 2352 sbinfo->gid = current_fsgid(); 2353 sb->s_fs_info = sbinfo; 2354 2355#ifdef CONFIG_TMPFS 2356 /* 2357 * Per default we only allow half of the physical ram per 2358 * tmpfs instance, limiting inodes to one per page of lowmem; 2359 * but the internal instance is left unlimited. 2360 */ 2361 if (!(sb->s_flags & MS_NOUSER)) { 2362 sbinfo->max_blocks = shmem_default_max_blocks(); 2363 sbinfo->max_inodes = shmem_default_max_inodes(); 2364 if (shmem_parse_options(data, sbinfo, false)) { 2365 err = -EINVAL; 2366 goto failed; 2367 } 2368 } 2369 sb->s_export_op = &shmem_export_ops; 2370#else 2371 sb->s_flags |= MS_NOUSER; 2372#endif 2373 2374 spin_lock_init(&sbinfo->stat_lock); 2375 if (percpu_counter_init(&sbinfo->used_blocks, 0)) 2376 goto failed; 2377 sbinfo->free_inodes = sbinfo->max_inodes; 2378 2379 sb->s_maxbytes = SHMEM_MAX_BYTES; 2380 sb->s_blocksize = PAGE_CACHE_SIZE; 2381 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 2382 sb->s_magic = TMPFS_MAGIC; 2383 sb->s_op = &shmem_ops; 2384 sb->s_time_gran = 1; 2385#ifdef CONFIG_TMPFS_POSIX_ACL 2386 sb->s_xattr = shmem_xattr_handlers; 2387 sb->s_flags |= MS_POSIXACL; 2388#endif 2389 2390 inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE); 2391 if (!inode) 2392 goto failed; 2393 inode->i_uid = sbinfo->uid; 2394 inode->i_gid = sbinfo->gid; 2395 root = d_alloc_root(inode); 2396 if (!root) 2397 goto failed_iput; 2398 sb->s_root = root; 2399 return 0; 2400 2401failed_iput: 2402 iput(inode); 2403failed: 2404 shmem_put_super(sb); 2405 return err; 2406} 2407 2408static struct kmem_cache *shmem_inode_cachep; 2409 2410static struct inode *shmem_alloc_inode(struct super_block *sb) 2411{ 2412 struct shmem_inode_info *p; 2413 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); 2414 if (!p) 2415 return NULL; 2416 return &p->vfs_inode; 2417} 2418 2419static void shmem_i_callback(struct rcu_head *head) 2420{ 2421 struct inode *inode = container_of(head, struct inode, i_rcu); 2422 INIT_LIST_HEAD(&inode->i_dentry); 2423 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); 2424} 2425 2426static void shmem_destroy_inode(struct inode *inode) 2427{ 2428 if ((inode->i_mode & S_IFMT) == S_IFREG) { 2429 /* only struct inode is valid if it's an inline symlink */ 2430 mpol_free_shared_policy(&SHMEM_I(inode)->policy); 2431 } 2432 call_rcu(&inode->i_rcu, shmem_i_callback); 2433} 2434 2435static void init_once(void *foo) 2436{ 2437 struct shmem_inode_info *p = (struct shmem_inode_info *) foo; 2438 2439 inode_init_once(&p->vfs_inode); 2440} 2441 2442static int init_inodecache(void) 2443{ 2444 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", 2445 sizeof(struct shmem_inode_info), 2446 0, SLAB_PANIC, init_once); 2447 return 0; 2448} 2449 2450static void destroy_inodecache(void) 2451{ 2452 kmem_cache_destroy(shmem_inode_cachep); 2453} 2454 2455static const struct address_space_operations shmem_aops = { 2456 .writepage = shmem_writepage, 2457 .set_page_dirty = __set_page_dirty_no_writeback, 2458#ifdef CONFIG_TMPFS 2459 .readpage = shmem_readpage, 2460 .write_begin = shmem_write_begin, 2461 .write_end = shmem_write_end, 2462#endif 2463 .migratepage = migrate_page, 2464 .error_remove_page = generic_error_remove_page, 2465}; 2466 2467static const struct file_operations shmem_file_operations = { 2468 .mmap = shmem_mmap, 2469#ifdef CONFIG_TMPFS 2470 .llseek = generic_file_llseek, 2471 .read = do_sync_read, 2472 .write = do_sync_write, 2473 .aio_read = shmem_file_aio_read, 2474 .aio_write = generic_file_aio_write, 2475 .fsync = noop_fsync, 2476 .splice_read = generic_file_splice_read, 2477 .splice_write = generic_file_splice_write, 2478#endif 2479}; 2480 2481static const struct inode_operations shmem_inode_operations = { 2482 .setattr = shmem_notify_change, 2483 .truncate_range = shmem_truncate_range, 2484#ifdef CONFIG_TMPFS_POSIX_ACL 2485 .setxattr = generic_setxattr, 2486 .getxattr = generic_getxattr, 2487 .listxattr = generic_listxattr, 2488 .removexattr = generic_removexattr, 2489 .check_acl = generic_check_acl, 2490#endif 2491 2492}; 2493 2494static const struct inode_operations shmem_dir_inode_operations = { 2495#ifdef CONFIG_TMPFS 2496 .create = shmem_create, 2497 .lookup = simple_lookup, 2498 .link = shmem_link, 2499 .unlink = shmem_unlink, 2500 .symlink = shmem_symlink, 2501 .mkdir = shmem_mkdir, 2502 .rmdir = shmem_rmdir, 2503 .mknod = shmem_mknod, 2504 .rename = shmem_rename, 2505#endif 2506#ifdef CONFIG_TMPFS_POSIX_ACL 2507 .setattr = shmem_notify_change, 2508 .setxattr = generic_setxattr, 2509 .getxattr = generic_getxattr, 2510 .listxattr = generic_listxattr, 2511 .removexattr = generic_removexattr, 2512 .check_acl = generic_check_acl, 2513#endif 2514}; 2515 2516static const struct inode_operations shmem_special_inode_operations = { 2517#ifdef CONFIG_TMPFS_POSIX_ACL 2518 .setattr = shmem_notify_change, 2519 .setxattr = generic_setxattr, 2520 .getxattr = generic_getxattr, 2521 .listxattr = generic_listxattr, 2522 .removexattr = generic_removexattr, 2523 .check_acl = generic_check_acl, 2524#endif 2525}; 2526 2527static const struct super_operations shmem_ops = { 2528 .alloc_inode = shmem_alloc_inode, 2529 .destroy_inode = shmem_destroy_inode, 2530#ifdef CONFIG_TMPFS 2531 .statfs = shmem_statfs, 2532 .remount_fs = shmem_remount_fs, 2533 .show_options = shmem_show_options, 2534#endif 2535 .evict_inode = shmem_evict_inode, 2536 .drop_inode = generic_delete_inode, 2537 .put_super = shmem_put_super, 2538}; 2539 2540static const struct vm_operations_struct shmem_vm_ops = { 2541 .fault = shmem_fault, 2542#ifdef CONFIG_NUMA 2543 .set_policy = shmem_set_policy, 2544 .get_policy = shmem_get_policy, 2545#endif 2546}; 2547 2548 2549static struct dentry *shmem_mount(struct file_system_type *fs_type, 2550 int flags, const char *dev_name, void *data) 2551{ 2552 return mount_nodev(fs_type, flags, data, shmem_fill_super); 2553} 2554 2555static struct file_system_type tmpfs_fs_type = { 2556 .owner = THIS_MODULE, 2557 .name = "tmpfs", 2558 .mount = shmem_mount, 2559 .kill_sb = kill_litter_super, 2560}; 2561 2562int __init init_tmpfs(void) 2563{ 2564 int error; 2565 2566 error = bdi_init(&shmem_backing_dev_info); 2567 if (error) 2568 goto out4; 2569 2570 error = init_inodecache(); 2571 if (error) 2572 goto out3; 2573 2574 error = register_filesystem(&tmpfs_fs_type); 2575 if (error) { 2576 printk(KERN_ERR "Could not register tmpfs\n"); 2577 goto out2; 2578 } 2579 2580 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER, 2581 tmpfs_fs_type.name, NULL); 2582 if (IS_ERR(shm_mnt)) { 2583 error = PTR_ERR(shm_mnt); 2584 printk(KERN_ERR "Could not kern_mount tmpfs\n"); 2585 goto out1; 2586 } 2587 return 0; 2588 2589out1: 2590 unregister_filesystem(&tmpfs_fs_type); 2591out2: 2592 destroy_inodecache(); 2593out3: 2594 bdi_destroy(&shmem_backing_dev_info); 2595out4: 2596 shm_mnt = ERR_PTR(error); 2597 return error; 2598} 2599 2600#ifdef CONFIG_CGROUP_MEM_RES_CTLR 2601/** 2602 * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file 2603 * @inode: the inode to be searched 2604 * @pgoff: the offset to be searched 2605 * @pagep: the pointer for the found page to be stored 2606 * @ent: the pointer for the found swap entry to be stored 2607 * 2608 * If a page is found, refcount of it is incremented. Callers should handle 2609 * these refcount. 2610 */ 2611void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff, 2612 struct page **pagep, swp_entry_t *ent) 2613{ 2614 swp_entry_t entry = { .val = 0 }, *ptr; 2615 struct page *page = NULL; 2616 struct shmem_inode_info *info = SHMEM_I(inode); 2617 2618 if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 2619 goto out; 2620 2621 spin_lock(&info->lock); 2622 ptr = shmem_swp_entry(info, pgoff, NULL); 2623#ifdef CONFIG_SWAP 2624 if (ptr && ptr->val) { 2625 entry.val = ptr->val; 2626 page = find_get_page(&swapper_space, entry.val); 2627 } else 2628#endif 2629 page = find_get_page(inode->i_mapping, pgoff); 2630 if (ptr) 2631 shmem_swp_unmap(ptr); 2632 spin_unlock(&info->lock); 2633out: 2634 *pagep = page; 2635 *ent = entry; 2636} 2637#endif 2638 2639#else /* !CONFIG_SHMEM */ 2640 2641/* 2642 * tiny-shmem: simple shmemfs and tmpfs using ramfs code 2643 * 2644 * This is intended for small system where the benefits of the full 2645 * shmem code (swap-backed and resource-limited) are outweighed by 2646 * their complexity. On systems without swap this code should be 2647 * effectively equivalent, but much lighter weight. 2648 */ 2649 2650#include <linux/ramfs.h> 2651 2652static struct file_system_type tmpfs_fs_type = { 2653 .name = "tmpfs", 2654 .mount = ramfs_mount, 2655 .kill_sb = kill_litter_super, 2656}; 2657 2658int __init init_tmpfs(void) 2659{ 2660 BUG_ON(register_filesystem(&tmpfs_fs_type) != 0); 2661 2662 shm_mnt = kern_mount(&tmpfs_fs_type); 2663 BUG_ON(IS_ERR(shm_mnt)); 2664 2665 return 0; 2666} 2667 2668int shmem_unuse(swp_entry_t entry, struct page *page) 2669{ 2670 return 0; 2671} 2672 2673int shmem_lock(struct file *file, int lock, struct user_struct *user) 2674{ 2675 return 0; 2676} 2677 2678#ifdef CONFIG_CGROUP_MEM_RES_CTLR 2679/** 2680 * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file 2681 * @inode: the inode to be searched 2682 * @pgoff: the offset to be searched 2683 * @pagep: the pointer for the found page to be stored 2684 * @ent: the pointer for the found swap entry to be stored 2685 * 2686 * If a page is found, refcount of it is incremented. Callers should handle 2687 * these refcount. 2688 */ 2689void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff, 2690 struct page **pagep, swp_entry_t *ent) 2691{ 2692 struct page *page = NULL; 2693 2694 if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 2695 goto out; 2696 page = find_get_page(inode->i_mapping, pgoff); 2697out: 2698 *pagep = page; 2699 *ent = (swp_entry_t){ .val = 0 }; 2700} 2701#endif 2702 2703#define shmem_vm_ops generic_file_vm_ops 2704#define shmem_file_operations ramfs_file_operations 2705#define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev) 2706#define shmem_acct_size(flags, size) 0 2707#define shmem_unacct_size(flags, size) do {} while (0) 2708#define SHMEM_MAX_BYTES MAX_LFS_FILESIZE 2709 2710#endif /* CONFIG_SHMEM */ 2711 2712/* common code */ 2713 2714/** 2715 * shmem_file_setup - get an unlinked file living in tmpfs 2716 * @name: name for dentry (to be seen in /proc/<pid>/maps 2717 * @size: size to be set for the file 2718 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size 2719 */ 2720struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags) 2721{ 2722 int error; 2723 struct file *file; 2724 struct inode *inode; 2725 struct path path; 2726 struct dentry *root; 2727 struct qstr this; 2728 2729 if (IS_ERR(shm_mnt)) 2730 return (void *)shm_mnt; 2731 2732 if (size < 0 || size > SHMEM_MAX_BYTES) 2733 return ERR_PTR(-EINVAL); 2734 2735 if (shmem_acct_size(flags, size)) 2736 return ERR_PTR(-ENOMEM); 2737 2738 error = -ENOMEM; 2739 this.name = name; 2740 this.len = strlen(name); 2741 this.hash = 0; /* will go */ 2742 root = shm_mnt->mnt_root; 2743 path.dentry = d_alloc(root, &this); 2744 if (!path.dentry) 2745 goto put_memory; 2746 path.mnt = mntget(shm_mnt); 2747 2748 error = -ENOSPC; 2749 inode = shmem_get_inode(root->d_sb, NULL, S_IFREG | S_IRWXUGO, 0, flags); 2750 if (!inode) 2751 goto put_dentry; 2752 2753 d_instantiate(path.dentry, inode); 2754 inode->i_size = size; 2755 inode->i_nlink = 0; /* It is unlinked */ 2756#ifndef CONFIG_MMU 2757 error = ramfs_nommu_expand_for_mapping(inode, size); 2758 if (error) 2759 goto put_dentry; 2760#endif 2761 2762 error = -ENFILE; 2763 file = alloc_file(&path, FMODE_WRITE | FMODE_READ, 2764 &shmem_file_operations); 2765 if (!file) 2766 goto put_dentry; 2767 2768 return file; 2769 2770put_dentry: 2771 path_put(&path); 2772put_memory: 2773 shmem_unacct_size(flags, size); 2774 return ERR_PTR(error); 2775} 2776EXPORT_SYMBOL_GPL(shmem_file_setup); 2777 2778/** 2779 * shmem_zero_setup - setup a shared anonymous mapping 2780 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff 2781 */ 2782int shmem_zero_setup(struct vm_area_struct *vma) 2783{ 2784 struct file *file; 2785 loff_t size = vma->vm_end - vma->vm_start; 2786 2787 file = shmem_file_setup("dev/zero", size, vma->vm_flags); 2788 if (IS_ERR(file)) 2789 return PTR_ERR(file); 2790 2791 if (vma->vm_file) 2792 fput(vma->vm_file); 2793 vma->vm_file = file; 2794 vma->vm_ops = &shmem_vm_ops; 2795 return 0; 2796} 2797